body {
    background: linear-gradient(135deg, #181c2b 0%, #232946 100%);
    min-height: 100vh;
    color: #f3f6fa;
}

.main-content, .addbook-container {
    max-width: 500px;
    margin: 80px auto;
    padding: 32px 32px 24px 32px;
    background: rgba(30,34,54,0.95);
    border-radius: 18px;
    box-shadow: 0 8px 32px #1e90ff22;
}

h1, h2, .site-title {
    color: #1e90ff;
    font-weight: bold;
    letter-spacing: 2px;
    text-shadow: 0 2px 8px #1e90ff44;
    animation: fadeInDown 1s;
    text-align: center;
}

.form-label, label {
    color: #f3f6fa;
}

input[type="text"], input[type="password"] {
    background: #232946;
    color: #fff;
    border: 1px solid #1e90ff;
    border-radius: 8px;
    margin-bottom: 10px;
}

input[type="text"]:focus, input[type="password"]:focus {
    border-color: #1e90ff;
    box-shadow: 0 0 8px #1e90ff88;
}

.add-btn, .btn {
    background: #232946;
    color: #fff;
    border: 1px solid #1e90ff;
    border-radius: 8px;
    transition: background 0.2s, box-shadow 0.2s, color 0.2s, transform 0.2s;
}

.add-btn:hover, .btn:hover {
    background: #1e90ff;
    color: #fff;
    box-shadow: 0 0 12px #1e90ff88, 0 0 2px #fff;
    transform: scale(1.08);
}

.error-message {
    color: #dc3545;
    text-align: center;
    margin-top: 12px;
}

@keyframes fadeInDown {
    from { opacity: 0; transform: translateY(-30px); }
    to { opacity: 1; transform: translateY(0); }
}